二叉树遍历+创建

数组存储二叉树(下标从1开始）。i>时父节点为i/2；当i2<=节点个数时，左子树为i2；当i2+1<=节点个数时，右子数为2i+1

void PreTra(int i){
	if(i >= len)
	    return ;
	printf("%c",a[i]);
	PreTra(i*2);
	PreTra(i*2+1);
	return ;	
}

void InTra(int i){
	if(i >= len)
	    return ;
    InTra(i*2);
	printf("%c",a[i]);
	InTra(i*2+1);
	return ;	
}

void LaTra(int i){
	if(i >= len)
	    return ;
        LaTra(i*2);
	LaTra(i*2+1);
	printf("%c",a[i]);
	return ;	
}


int main(){
	int i;
	char ch;
	len = 1;
	while(ch = getchar()){
		a[len++] = ch;
		if(ch == '
')
		    break;
	}
	len --;
	PreTra(1);
	printf("
");
	InTra(1);
	printf("
");
	LaTra(1);
	return 0; 
}

先序递归创建二叉树（链表）

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
struct node{
	char data;
	node * left;
	node * right;
};

void CreateTree(node ** p){
	char ch = getchar();
	if(ch == ' '){
	    *p = NULL;
		return ;
	}
	(*p) = (node*) malloc(sizeof(node));
	(*p)->data = ch;
	CreateTree(&((*p)->left));
	CreateTree(&((*p)->right));
}

void PreTra(node *p){
	if(!p)
	    return ;
	printf("%c",p->data);
	PreTra(p->left);
	PreTra(p->right);
}

int main(){
	char ch;
	node * tree;
	CreateTree(&tree);
	PreTra(tree);
//	printf("Tree
");
	return 0;
}